I think I may have found a bug today.
Working on a project today I tried to export Lightwave Pointcache MDD for a mesh. I received the error messages that you see in the pictures I attached.
At first I thought this was just an issue that was specific to my project but that is not the case.
I installed the latest version of Blender 2.8 and the issue persists on it as well. I also tried creating a new project with nothing on it except that default cube and the issue happens there also.
I have tested this issue on 3 different computers, one being a Mac using the latest OS X, the other two being a desktop and a laptop both using Windows 10 with all updates installed. The issue is happening on all 3 computers.
So is Lightwave Pointcache MDD simply bugged on the current version of 2.8? Is there a workaround?
Is there any additional specific information that I can provide that might help?